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Author: search.filters.author.Mahendra, K.Subject: search.filters.subject.Dyes

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    Effect of methyl orange dye molecule on the structural, optical and electrical properties of the KHOOD single crystals
    (Springer, 2020) Mahendra, K.; Pujar, S.; Udayashankar, N.K.
    In the present investigation, synthesis of pristine and methyl orange dye-doped potassium hydrogen oxalate oxalic acid dihydrate (KHOOD) single crystals are reported. In this study, the structural properties of the crystals were investigated using powder XRD and the effect of dye incorporation on the KHOOD crystal was explored in detail. The effect of dye molecule on the optical absorption of the crystal was studied and the optical band gap was calculated using Tauc relation and presented in detail. Further, the effect on emission and mechanical properties of the crystals were also explored after doping with the dye molecule. Furthermore, the crystals were also studied electrically by subjecting to varying electrical frequencies (A.C) and the properties of pristine and doped crystals were compared and explained in detail. The modulus properties of the crystals were studied and compared. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
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    Effect of Erioglaucine dye dopant on the structural, optical, mechanical, electrical and nonlinear properties of ammonium dihydrogen phosphate single crystal
    (Elsevier B.V., 2020) Fernandes, J.M.; Mahendra, K.; Udayashankar, N.K.
    The structural, optical, mechanical, electrical and nonlinear properties of standard Ammonium Dihydrogen Phosphate (NH4H2PO4, ADP) single crystals incorporating organic Erioglaucine dye dopant are presented. The effect of Erioglaucine dye dopant at varied concentration on these properties has been investigated through measurement of powder X-Ray Diffraction (XRD), UV–Vis and photoluminescence spectroscopy, Vickers microhardness, light dependent I–V measurements and Second Harmonic Generation studies. These measurements reveal that doping with increasing dye concentration of Erioglaucine leads to change in properties of the ADP single crystals, making them suitable for optoelectronic applications. The Erioglaucine doped ADP single crystals were grown using solvent evaporation technique at room temperature. Optical properties like absorbance and emission of these crystals are determined using UV–vis and photoluminescence spectroscopy, respectively. Optical bandgap and photoluminescence of the crystals are found to increase with dye doping, indicating their suitability in photonic applications. The mechanical properties of the crystals are determined using Vickers microhardness measurement technique. Light dependent I–V measurements exhibit negative photoconductivity behavior of the ADP crystals. However, the current through the crystals is observed to increase with increase in doping concentration of the Erioglaucine dye. Second Harmonic Generation studies show enhancement in nonlinearity for doped crystals. Our experiments indicate gradual variance in the crystallinity, emission, hardness, conductivity and nonlinearity of the sample with change in dye concentration. © 2020 Elsevier B.V.
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    Efficient removal of toxic dyes and nitrophenol using Graphene Oxide-ZrO2 hybrid catalysts
    (Elsevier Ltd, 2025) Amudha, A.; Mahendra, K.; Yashodhara, I.; Pattar, J.; Anil Rao, H.N.; Shashikala, H.D.; Hosakoppa, S.N.
    In the current study, efficient removal of industrial dyes and nitrophenol by ZrO2–GO catalyst has been reported. ZrO2–GO nanoparticles were prepared using the hydrothermal technique and are characterized using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Transmission Electron Microscopy (TEM), Photoluminescence (PL), Raman, and UV–visible spectroscopy techniques. The ability of the nanoparticles to degrade Methylene Blue (MB), Crystal Violet (CV), and Nitrophenol (NP) was examined for their photocatalytic activities. Results revealed that there is an increase in the crystallite size and pore size increased almost 2 times after adding 2 % GO in ZrO2. The addition of GO into ZrO2 also caused a decrease in the PL intensity and energy gap indicating an increase in the charge carriers. ZrO2–GO nanoparticles showed photocatalytic degradation of 90 % (70 min), 98 % (90 min), and 70 % (120 min) for MB, CV, and NP respectively. © 2025 Elsevier B.V.